Instruments



Jan. 5, 1960 M. MoLLlcK INSTRUMENTS Filed March 25, 1958 v INVENTOF mgm mlldb PJM, gm, Wmv/mma@ ATToRNE//YS United States Patent O INSTRUMENTS Milton Mollick, Allentown, Pa., assign'or to American Machine and Metals, Inc., New York, N.Y., a corporation of Delaware v Application March 2s, 195s, serial No. 123,762 6 claims. (ci. 137-85) This invention relates to pneumatically operated instruments and particularly to a non-bleed relay for use therein.

A variable condition, such as temperature, pressure, ilow or the like, can be used to position avalve or a iiapper and nozzle relative to each other so as to vary the air pressure in the nozzle in response to variations in the variable condition.

The nozzle may be connected to a supply of air through a restriction so that, for example, as the valve or flapper is moved to closed position relative to the nozzle by a change in the variable condition, air pressure in the nozzle will rise and as the valve or flapper is moved away from lthe nozzle by the variable condition, air pressure in the nozzle will decrease. In order to utilize the nozzle air pressure and produce an ampliiied controlling pressure proportional to the nozzle air pressure, a device known as a pressure relay is normally utilized.

In order to keep the air consumption of the relay at a minimum and reduce the cost of operating the instrument, a relay known as Va non-bleed relay is desirable for some purposes since it does not consume air when the pressure in the nozzle is low.

One of the objects of this invention is to provide an improved non-bleed pressure relay which has a high speed ofresponse and is quiet in operation.

A further object of this invention is to provide a nonbleed pressure relay which consumes very little air. A further object of this invention is to provide a non-bleed relay having a Vrigid base which can be economically made.

A still further object is to provide a non-bleed relay in which equilibrium is reached without any vibration by utilizing darnpening means.

In a preferred aspect, the non-bleed pressure relay includes an expansible and contractible condition responsive element. An air supply line is connected to an air outlet, and the flow of air from the supply to the outlet is controlled by a valve. A valve stem is connected to the valve. A bellows having an exhaust passage is provided and the valve stem controls the flow of air through this exhaust passage. The bellows also includes a plunger with slidable friction sealing means. This plunger is movable in response to the movement of the condition responsive element. The plunger has a restricted aperture therein leading from the downstream side of the valve means to the bellows, so that air will enter the bellows to expand the same. This expansion urges vthe plunger in a downstream direction beyond the free end of the valve stem.

The base of the non-bleed pressure relay involved herein is rigid and can be removably mounted in a casing44 in which the various measuring and control elements with which it is used are mounted. Suitable connections are made to the supply and output lines and to the various elements of the instrument.

These and other objects, advantages and features of the invention will become apparent from the following detailed description and drawings, which are merely exemplary.

In the drawings:

Fig. 1 is a sectional view of a preferred form of the non-bleed pressure relay of the invention; and

lFig. 2 is an enlarged view of the preferred form of needle point for the tree end of the valve stem.

As the flapper or valve and nozzle (these elements are not shown) are moved relative to each other by a change in thevvariable condition or measured variable, there will be a change in pressure in the nozzle passage. The nozzle passage is connected to the pressure responsive means of the pressure relay, shown as capsule or diaphragm 10 in Fig. 1, through passages 11 and 12. As the pressure changes in the pressure responsive means of the relay, the output pressure passage will be connected to the supply pressure or to the atmosphere as determined by the nozzle pressure.

The relay is preferably mounted on a rigid base 13 formed from bar stock having a uniform transverse cross section. The bar stock may be formed by any suitable metal forming operation and cut to the desired length.

Air passages and chambers can be formed in base 13 by suitable cutting machines or drills. For example, a supply pressure passage 14 and an output passage 15 may be drilled in any suitable manner. In the form shown, these passages are drilled from opposite ends of the base 13 and are skewed relative to each other, so as to permit use of a minimum thickness bar stock. The threaded connecting apertures 16 and 17 must be of a predetermined length to provide a suitable connection.

Also formed in base 13 is the valve chamber 18 valve seat 19 and bellows unit receiving chamber 20. Chambers 18 and 20 are axially aligned and are internally threaded at their outer ends. Screw plug means 21 is threaded in the outer end of valve chamber 18 and has a Well 22 therein carrying valve spring 23, said valve spring bearing against the valve 24. Valve 24 has an extension 25 which is within the coils of spring 23 so as to ensure linear movement of valve 24.

The pressure responsive means 10 can have its outer end connected to pressure responsive means mounting plate 26, said mounting plate being spaced from base 13 by spacer posts 27 (only one of which is shown). Diaphragm stud 28 can be adjustably mounted on plate 26 by means of nuts 29, 30. Capsule or wafer 31 has its interior connected through passages 11 and 1-2 to the nozzle passage or to the control air source. Button or plate 32 is secured to the opposite side of capsule 31.v

from stud 28.

Threadingly mounted in chamber 20 is a bellows unit, designated generally at 33, which includes a hollow casing 34 having flanges 35 and 36 on the outside between which is secured a wafer or capsule 37. A plunger 38 is slidably mounted Within passage 39 in casing 34 and frictionallyy engages said passage through O-rings 40 and 41 which prevent the leakage of air between the passage 39 and post plunger 38. The construction using 0-rings also serves to dampen the motion of plunger 38. Plunger 38 has a flange 42 which engages flange 36 when the plunger moves in an upstream direction toward the valve. The downstream side ange 42 rests against or is in contact with plate 32 on capsule 31. A` longitudinal passageway 43 having a reduced portion 44 is formed in the plunger 38. Reduced portion 44 forms a needle valve seat 45 for needle point 46 on valve stem 47. Restricted apertures 48 connect passage 39 with passageway 43.

When there is no pressure exerted on diaphragm 31, valve 24 will be in contact with valve seat 19 so as to close the connection between supply pressure passage 14 and output pressure passage 15. At the same time needle point 46 will be spaced from valve seat 45 to permit Patented Jan. 5, 19.60v

output passage 1S to be in communication with the atmosphere through passages 49 in plunger 38, thereby venting the pressure in passage 15.

As the pressure in passages 11 and 12 increases, capsule 31 expands forcing plunger 38 in an upstream direction. Valve seat 45 engages needle point 4e and forces valve stem 47 and valve 24 to open position against the action of spring Z3, thereby connecting the supply pressure passage '1d with the output pressure passage 15. This also results in air entering the interior of capsule 37 through restricted passages 4S causing capsule 37 to expand until the pressure in capsules 37 and 31 is equalized.

lt has been found desirable to form a notch l! in the needle point, so as to provide a very small exhaust of air so as to get equilibrium without any dead spot.

The above described construction results in a non-bleed relay having a rapid speed or response which is economical to manufacture and which is not subject to constant breakdowns. Also it is quiet in operation and will not flutterf It should be apparent that details of the invention can be varied without departing from the spirit of the invention, except as set forth in the appended claims.

What is claimed is:

l. ln a non-bleed pressure relay, the combination including an expansible and contractible condition responsive element, a source of air supply, an air outlet, valve means connecting said source and said outlet for controlling the passage of air therethrough, an exhaust valve connected to said valve means, and a bellows arrangement having an exhaust passage controlled by said exhaust valve` said bellows arrangement including a pli nger with slidable friction sealing means, said bellows arrangement also including expansible and contractible means, said plunger having a restricted aperture leading from the downstream side ot said valve means to said expansible and contractible means.

2. in a non-bleed pressure relay` the combination including an expansible and contractible condition responsive element. a source of air supply, an air outlet, valve means connecting said so :e and said outlet for controlling tlie passage of air therethrough, a valve stem connected to said valve means, and a bellows arrangement havin" an exhaust passage controlled by said stem, said bellows arrangement having a plunger with slidable fric-tion sealing means which is movable in response to movement of said condition responsive means to control a'd exhaust passage in cooperation with said stern and also to cause said valve stern to move in an upstream direction to open said valve means and allow the air to ow from said supply to said outlet, said bellows arrangement also including a. bellows, said plunger having a restricted aperture leading rom the downstream side of said valve means to said bellows.

3. In a non-bleed pressure relay, the combination including an expansible and contractible condition responsive element, a source of air supply, an air outlet, a valve chamber connecting said source and said outlet, a valve biased to closed position, a valve stem connected to said valve, and a bellows arrangement having an exhaust passage controlledA by said stem, said bellows arrangement including a plunger with slidable friction sealing means, said plunger being movable. in response to movement of sai-:l condition responsive means to control said exhaust passag cooperation with said stern, and also to cause said valve stern to move in an upstream direction to open said valve and allow the air to ow from said supply to said outlet, said bellows arrangement also including a bellows, said plunger having a restricted aperture leading from the downstream side of said valve means to said bellows.

4. In a non-bleed pressure relay, the combination including an expansible and contractible condition responsive element, a source of air supply, an air outlet, a bar stock body having an air supply and an air outlet passage therein, a valve chamber in said body connecting said air supply passage and said air outlet passage, valve means in said valve chamber for controlling the passage of air through said chamber, a valve stem connected to the downstream side of said valve means, and a bellows arrangement having an exhaust passage controlled by said stein, sind bellows arrangement including a plunger with slidable friction sealing means, said plunger being movable in response to movement of said condition responsive elements to control said exhaust passage in cooperation with said stem, and also to cause said valve stem to move in an upstream direction to open said valve means and allo'w the air to flow from said supply to said outlet, said slidable friction sealing means including a pair of spaced O-rings on the outer peripheral surface of said plunger, said bellows arrangement also including an expansible and contractible bellows, and said plunger having a restricted aperture leading from the downstream side of said valve means to the interior of said bellows.

5. In a non-bleed pressure relay, the combination including a diaphragm which is expansible and contractible in response to change in the condition being controlled, a source of air supply, an air outlet, valve means connecting said source and said outlet for controlling the passage of air therethrough, spring means biasing said valve means to closed position, a valve stern connected to said valve means, and a bellows arrangement having an exhaust passage controlled by said stem, said bellows arrangement including a plunger with slidable friction sealing means which is movable in response to movement of said condition responsive means to control said exhaust passage in cooperation with said stem, and also to cause said valve stein to move in an upstream direction to open said valve means against the action of said spring means and allow the air to flow from said supply to said outlet, said bellows arrangement also including a bellows, said plunger having a restricted aperture leading from the downstream Side of Said valve means to said bellows.

6. 1n a non-bleed pressure relay, the combination including an expansible and contractible condition responsive element, a source of air supply, an air outlet, valve means connecting said source and said outlet for controlling the passage of air therethrough, a valve stem connected to' said valve means, and a bellows arrangement having an exhaust passage controlled by said stern, said bellows arrangement including a plunger with slidable friction sealing means which is movable in response to movement of said condition responsive means, said plunger including an internal valve seat adapted to lengage the downstream end of said stem so as to control said exhaust passage in cooperation with said stem, and also to cause said valve stem to move in an upstream direction to open said valve means and allow the air to Flow from said supply to said outlet, said bellows arrangement also including a bellows, said plunger having a restricted aperture leading fro'm the downstream side of said valve means to said bellows.

References Cited in the le of this patent UNITED STATES PATENTS 2,226,865 Kirchen Dec. 31, 1940 2,431,297 Moore e Nov 18, 1947 2,461,026 Belyeau Feb. 8, 1949 2,818,876 Le Van e Ian. 7, 1958 2,825,354 Du Bois Mar. 4, 1958 

